Why have they stopped going? Perhaps it has something to do with the failure of the RC church to address the hundreds of pedophiles to whom people are confessing their sins.
Just a guess
Add to the fact that the Church has been inundated with so many of the "touchy feely" liberal priests who preach all about God's relentless love, but leave out accountability for sin completely in their homilies.
With many liberal priests homilies, its as if sin and evil don't exist.
4 percent of the priests have been guilty of this type of misconduct, most done during the 60s and 70s.
96 percent of the priests have not ever done anything scandalously wrong.
96 per cent of the men do their job, and yet people who say things like this seem to want to throw away the 96 percent and act like the whole church is manned only by the 4 percent.
What an unbalanced, uncharitable worldview.
It fell off long before that. My guess - from a post Vat II brat perspective - is that in a world that has no shame, where love the sinner and hate the sin has become the culture more than instructing on what sin is, people don't quite understand that they are sinning.
And honestly, I go to Confession often and I don't remember the last time I didn't have to wait in line. I think it really depends on where you are. The people who flock to parishes with AmChurch type priests aren't likely to take advantage of confessing sins.